If you want to get rich, start by studying the people who have already done so.

"The only person who can teach you how to think like a millionaire is a millionaire," writes Steve Siebold in his book, " How Rich People Think."

The same could be said about billionaires.

Below, we've rounded up 11 habits of self-made billionaires. You may notice that none of them require dramatic life changes — a few tweaks here and there to your daily routine could result in huge gains.

And then there's the Giving Pledge, which Warren Buffett and Bill and Melinda Gates created in order to invite the world's wealthiest people to pledge more than half of their wealth to charitable causes either during their lives or in their wills. Some have even pledged to give away more than 99% of their fortunes.

They pursue their passion

"You've got to find what you love," Apple cofounder Steve Jobs said during his 2005 commencement address to the graduates of Stanford University. "The only way to do great work is to love what you do. If you haven't found it yet, keep looking. Don't settle. As with all matters of the heart, you'll know when you find it."

Jobs wasn't the first to emphasize the importance of pursuing your passion. Author Napoleon Hill, who studied over 500 incredibly rich people in the early 20th century, wrote in his bestseller, " Think and Grow Rich": "No man can succeed in a line of endeavor which he does not like."

They read

Investing legend Warren Buffett reportedly spends about 80% of his day reading, and continues to include book recommendations in his annual shareholder letters.

In 2015, Facebook's Mark Zuckerberg resolved to read a book every two weeks ... Media mogul Oprah Winfrey selects a book every month for readers to discuss online as part of " Oprah's Book Club 2.0," and when tech billionaire Elon Musk is asked how he learned to build rockets, he reportedly answers, "I read books."

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They develop multiple streams of income

Richard Branson, the billionaire chair of the Virgin Group, epitomizes this habit, Corley explains in " Change Your Habits, Change Your Life." Branson has overseen about 500 companies and his brand is on somewhere between 200 and 300 of them.

Branson "puts the rich habit of having multiple streams of income on steroids," Corley writes. "His desire to expand the Virgin brand is really a desire to expand his streams of income. Branson learned very early on that this rich habit creates the most wealth."

Mark Zuckerberg has been working for himself since age 19, when he first launched Facebook as a Harvard sophomore in 2004. Snapchat CEO Evan Spiegel, who is the youngest billionaire in the world, had a similar path — he created the popular photo-sharing app with two of his former Stanford classmates and has been his own boss ever since.

"It's not that there aren't world-class performers who punch a time clock for a paycheck, but for most this is the slowest path to prosperity, promoted as the safest," says self-made millionaire Steve Siebold, who has also studied over 1,200 wealthy individuals. "The great ones know self-employment is the fastest road to wealth."

They hang out with other successful people

The wealthiest people like to stand next to the smartest person in the room, notes author and podcast host James Altucher: "Harold Ramis did it (Bill Murray). Steve Jobs did it (Steve Wozniak). Craig Silverstein did it (Who? Larry Page). Kanye West did it (Jay-Z)."